Sewing machine



J. G. ATTWOOD SEWING MACHINE Feb. 26, 1946.

Filed Jan. 28, 1943 sheets-sheet 1 llllI I INVENTOR 6. Arm 00 ATTORNE Feb. 26, 1946. J. G. ATTWOOD SEWING MACHINE Fil ed Jan. 2a, 1945 4 Sheets-Sheet 2 INVENTOR. Ji/A/ 6 Arr/400p ATTOfPZVE'Y NNQQ J.. G. ATTWOOD SEWING MACHINE Feb. 26, 1946.

Filed Jan. 28, 1943 4 Sheets-Sheet 3 INVENTOR fa/m/ 6, Arrwoap A TT ORNE Y Feb. 26, 1946.

J. G. ATTWOQD SEWING MACHINE Filed Jan; 28, 1943 4 Sheets-Sheet 4 2 6 c" J4 4 ATTORNE Patented Feb. 26, 1946 2,395,653 SEWING MACHINE John G. Attwood, Oak Park, Ill., assignor to Union Special Machine Company,

poration of Illinois Chicago, 11]., a cor- Appllcation January 28, 1943, Serial No. 473,804

' 4 Claims. (01.112-256) This invention relates to sewing machines of the lockstitch type and more particularly to improved means for insuring proper lubrication of the raceway of the rotary hook of such a ma chine.

An object of the invention has been to provide efiective means, which is simple both in construction and operation, for supplying a predetermined amount of lubricant to the raceway of a rotary hook upon the rotation of its rotary component. Toward this end the invention contemplates the provision of centrifugal oil pumping means in close association with the rotary hook, which is operable only upon rotation of the hook, to draw oil from a relatively large reservoir beneath the work support and deliver it at a predetermined rate to the raceway.

As a special feature of the invention, the pumping means has incorporated directly therein means for restricting and controlling the fiow of the lubricant. This fiow restricting means is of a fixed orifice type but is subject to simple modiflcation in the construction, assembly, or testing of the machine to provide precisely the correct rate of flow. Due consideration may be given in the formation or modification of the flow restricting means to the character of lubricant to be employed and the normal range of speeds at which the machine is tobe operated. However, it has been found practicable with the improved arrangement to so construct the pumping and fiow restricting means 'that they will function satisfactorily with reasonable variation both. in the type of lubricant employed and in thespeed of operation of the machine.

Another feature of the invention is the arrangement, in association with the centrifugal pump andfiow restricting means set forth above, of a lubricant reservoir of relatively large capacity' and simple construction Just beneath the work supporting surface of the machine. This reservoir is so disposed and connected as to deliver lubricant in without the aid of gravity, axially into the end of a hollow shaft which carries the rotary component of the book. The reservoir is readily accessible for filling and is provided with convenient means for gauging its contents. Provision is also made for proper venting of the reservoir while, at the same time, permitting it to be tilted with the machine without danger of-spillins oil.

Other objects, features and advantages of the invention will appear from a detailed description of an illustrative form of the samewhich Fig. III is a detail view in transverse section along the line III-.III of Fig. I;

response to the pump action with or I Fig. IV is an enlargedv detail view, partly in side elevation and partly in longitudinal section, showing a rotary hook and its operating shaft embodied in the illustrative machine;

Fig. V is an end view of a screw plug embodied in the hook unit;

Fig. V1 is a longitudinal section through the screw plug;

Fig. VII is a view, partly in side elevation and partly in longitudinal section, showing the work supporting portion of a machine embodying a modified form of the invention, and

Fig. VIII is a bottom plan view of the machine illustrated in Fig. VII with portions'broken away and shown in section for clarity of illustration.

Referring now to Figs. I to VI, inclusive, of the drawings, there is illustrated a machine of the general type disclosed in the patent to Christensen et al. No. 2,113,572, granted April 12, 1938, having applied thereto the improvements of the present invention. This machine has a main frame comprising a work supporting base portion l8, a hollow vertical standard I l rising from one end of the work support, and an overhanging arm l2 extending laterally from the upper end of the standard and carrying a needle head It at its free end. Within the needle head there is mounted a vertically reciproc'able needle bar it carrying at its lower end a needle l5 adapted to be passed repeatedly through the work, carried by the work support It], in the course of forming a seam. A presser bar it, movable vertically in the needle head, is normally urged downwardly by a spring (not shown) to carry a presser foot ll, mounted upon its lower end, into engagement with the work on the work support. Any convenient means may be provided for lifting the presser bar, whenever desired, to release the work. The means for operating the needle bar may likewise be of any well known construction, such as that disclosed in the above-mentioned Christensen patent; It may suitably be operated bya shaft i8 extending longitudinally through the arm [2 and passing outwardly through a bearing in the rear wall of the standard ll beyond which there may be secured to the shaft a combined hand wheel and pulley l9 in turn connected with a gear 22 secured to a shaft 23. The latter extends through a bearing in a wall 24 of the base of the machine and is journaled in suitable bearings carried by the work support, including a bearing 25 adjacent its outer end. A portion of the shaft passes through a small housing 26 forming part of the base beneath the work support. Within the housing 26 a gear 21 is secured to the shaft 23 and meshes with a gear 28 secured to a hook supporting shaft 29. This latter shaft is mounted in a long hearing sleeve 30 and also has its inner end journaled in a bearing sleeve 3| mounted in a wall of the housing 26. The gearing 21, 28 is such that the shaft 29 is given two revolutions for each revolution of the shafts i8 and 23. At its forward end the shaft 29 carries a rotary hook memher or component 32 within which is mounted a stationary component in the form of a bobbin case holder 33 (see Fig. IV). This bobbin case holder is provided with a rib 34 having bearing engagement with a raceway 35 in the rotary component of the hook. An arm 36 (Fig. II) serves to retain the stationary component against rotation. It will 'be understood that the rotary hook cooperates with the needle in a c'onventional manner to form lock stitches. Any suitable means may be provided for advancing the work in relation to the stitch forming devices. For this purpose a suitable feed dog (not shown) may be mounted upon a feed bar 31 arranged to be lifted and lowered by means of a crank element 38, at the end of the shaft 23, and to be given its feed stroke and return movement by an cecentric secured to the shaft 23, at an intermediate point, and cooperating with a strap 39. For further details as to the construction and operation of this feed mechanism, reference may be had to said Christensen patent hereinabove mentioned and to the patent to Sauer et al., No. 2,035,508, granted March 31, 1936, which discloses the illustrated mechanism for varying the stroke of the feed dog.

For the lubrication of various portions of the operating or drivenparts the lower end of the hollow standard II is closed by a bottom plate Ha which permits the retention of a suitable lubricant to be dispersed by the operation of the driving gears. The housing 26 is similarly closed by a bottom plate 26a to retain a suitable lubricant around the gears 21' and 28. Bearing sleeve 36 may be lubricated by oil introduced into a small reservoir 390 through an opening normally closed by a screw cap or 'plug 30b. This reservoir may be filled when the machine is tilted back on its hinges.

We come now to the improved means for delivering a proper amount of an appropriate lubricant to the raceway 35 of the rotary hook. For this purpose a. reservoir M is suitably mounted on the under side of the work support I0. A light, stainless oil is preferably employed in this reservoir. The reservoir may be of any suitable construction and formed of. metal or a plastic or other appropriate material. As illustrated in Figs. I, II and 111, it may suitably be of rectangular form and provided with. a flange 4| around its top adapted to be secured by-screws 42 to the under surface of the work support. A gasket #3 may be provided to effect a seal between the reservoir and the work support. voir may be filled periodically through an opening in the work support adjacent the vertical standard II, this opening being normally closed by a screw plug 44. This screw plug may suitably have threaded engagement with a sleeve 65 mounted in an opening in the work support and carrying a screen or other strainer 46 at its bottom. Large particles of foreign matter may thus be eliminated from the oil introduced into the reservoir. The quantity of oil present in the reservoir may suitably be indicated by means of a gauge ll which, as shown, may be in the form of a transparent plug such as disclosed in the patent to Sauer No. 2,301,460, granted November 10, 1942 having an inclined lower end with suita-ble indicating lines or grooves 48 to show the depth of the oil in the reservoir. A vent passage 49 (Figs. II and III) may be provided in the under surface of the work support over the reservoir to permit the free passage of air into and out of the reservoir. This passage extending forwardly toward the front of the machine permits the latter to be tilted back on its supporting hinges without danger of spilling the oil.

Through a small opening in the end of the reservoir, there is passed into the latter a small tube 50 having a tight fit with the wall of the reservoir to prevent the escape of oil therearound. The inner end 5! of this tube is preferably bent (as indicated in Figs. I and III) to carry its intake end to a point near the bottom. of the reservoir. The outer end of tube 50 is connected by a coupling 52 with a nipple 53 having threaded engagement with a cap 54 fitted snugly over the end of the bearing sleeve 31.

The hook shaft 29 is of hollow construction and has a longitudinally extending bore 55 throughout its length. At its outer end the shaft is provided with an enlarged head portion 56 on which is mounted the rotary component 32 of the hook. Member 32 may be secured to the shaft by means of screws 51, as shown in Fig. 11. At its outer end the bore 55 of the hook shaft is tapered outwardly to provide a frusto-conical portion 58. This frusto-conical portion of the bore snugly receives a correspondingly shaped portion 59 of a screw plug 69 (Figs. IV and VI). The plug is provided with threads 6| cooperating with internal threads in a reduced portion 62 of the bore of the shaft, the plug being turned until the above-mentioned frusto-conical surfaces are brought into firm engagement. The screwthreaded end of the plug is slotted, as indicated at 63', to provide a certain amount of springiness, which affords a locking action to prevent the accidental turning of the plug. In the plane of the slot 63 there is provided a longitudinally ex tending groove 64 along one side of the plug from its inner end to a point adjacent the conical head 59. From this point ethe bottom of the groove is gradually curved outwardly until it disappears at the surface of the plug at a point about midway of the length of its frusto-conical portion. At the inner, smaller end of the frusto-conical portion there is provided an annular groove 65 extending completely around the plug. A small groove or indentation 66 is formed along the face of the The reserfrusto-conical portion 59, thereby forming a restricted passage from the annular groove 85 to the outer end of the plug. The groove 66 may, if desired, be formed in the surface 68 instead of in the surface of the portion 59 of the plug.

The operation of the foregoing construction is as follows: In the course'oi' stitch'formation, it

will be understood that the rotary hook is revolved at a high speed of, say, between 7000 and 10,000 R. P. M. At such speeds a substantial centrifugal pumping action will be created by the outwardly inclined passage formed by the groove 66. As a result, a suction will be created assume beyond the end of the shaft. From this recess the oil will be thrown by centrifugal action through a passage 68 from which it will be discharged into a passage 69 and delivered to the hook raceway. Accurate control of the quantity of lubricant so delivered by the pump action of the groove 66 may be effected by varying the cross-sectional area of this groove. Starting with a groove of insuiiicient cross-sectional area to supply the requirements of the hook raceway, the groove may be enlarged by means of a file or similar implement until it is capable of delivering the correct amount of lubricant. Should it be found that, due to wear or the like, an excess amount of lubricant is delivered, the size of the passage 66 may be reduced by grinding the surface 59 of the plug slightly to permit the plug to enter the end of the shaft a somewhat greater distance. It will :be understood that in the use Of the device, no adjustment of the plug is contemplated. It is screwed in as tightly as required to cause its conical surface 59 to seat firmly against the surface 58 of the shaft bore. Thus a fixed orifice is provided once the depth or size of the groove 66 has been established. If desired, only a portion of the groove 66 need be of a definitely restricted cross-section, the balance of the groove being of a somewhat larger cross-section. Having determined the proper cross-sectional area of the groove 66, or a restricted portion of it, for use under particular conditions as to normal speed of operation of a machine, and the type of lubricant normally employed for the hook raceway, it is readily possible to manufacture a large number of similar machines'capable of supplying the correct amount of lubricant to the raceway.

In Figs. VII and VIII there is shown a slightly modified construction in which an oil reservoir of somewhat difierent form is employed. In other respects the modified machine may be of the same construction as that above described. In lieu of the rectangular reservoir of the first embodiment, there may be provided a cylindrical or tubular reservoir in which may, for convenience, be formed of a simple section of pipe and which, for accessibility and freedom from interference with other parts, may be disposed at an angle to the length of the base. The forward end of this reservoir is preferably disposed at slightly less than a right angle to the axis of the reservoir, corresponding with the angular disposition of the reservoir itself, and is arranged to fit snugly over a cap H which is in turn fitted over the end of a bearing sleeve Bla in which is journaled the inner end of a hollow shaft 29a. A passage 12 extending through the cap H serves to deliver lubricant from'the interior of the reservoir to the interior of the cap, through which it is supplied to the raceway in the manner hereinabove explained. At its opposite end the reservoir may be closed by a tightly fitting plug 73, an extension of which is provided with a vertical passage 14. The upper end of the latter may be screw-threaded to receive the lower screw-threaded end of a sleeve element 15 which serves to clamp the inner end of the reservoir against the under side of the work sup port. Element 15 may in turn be provided with a threaded bore adapted to receive a removable screw plug 16. Oil may be introduced into the reservoir upon the removal of the screw plug it. The latter may, if desired, be formed with an extension Tl serving as a gauge for indicating the amount of lubricant in the reservoir. A vent tube 13 extending upwardly and outwardly from the reservoir adjacent its top serves to vent the same in a manner permitting tilting of the machine without danger of spilling oil from the reservoir.

Since the operation of the modified construction is substantially the same as hereinabove described with respect to the first embodiment of the invention, a resume of its operation'is believed to be unnecessary.

While several illustrative embodiments of the invention have been described in considerable detail, it will be understood that various changes may be made in the construction and arrangement of the various parts without departing from the general principles and scope of the invention as defined by the appended claims.

I claim:

1. In a sewing machine having a frame providing a work support, a rotatable hollow shaft journaled in said frame beneath said work support, said shaft having a longitudinally extending bore, a rotary hook having a rotary component mounted for rotation with said shaft, a stationary component within said rotary component and having bearing surfaces in cooperation therewith, an oil reservoir beneath said work support, a conduit connecting the bore of said shaft with said reservoir, a portion of the surface of said bore sloping away from the axis of said shaft, a plug having a surface corresponding with said portion of the bore surface and seated firmly against the same, and one of said surfaces having a groove extending from a point of relatively small radius to a point of relatively large radius providing a restricted passage between said surfaces communicating at its end of relatively small radius with said bore and at its other end with said bearing surfaces.

2. In a sewing machine having a frame pro-' viding a work support, a rotatable hollow shaft Journaled in said frame beneath said work support, said shaft having a longitudinally extending bore, a rotary hook having a rotary component mounted for rotation with said shaft, a stationary component within said rotary component and having bearing surfaces in cooperation therewith, an oil reservoir beneath said work support, a conduit connectingthe bore of said shaft with said reservoir, a portion of the surface of said bore sloping away from the axis of said shaft, a plug having a surface corresponding with said portion of the bore surface and'seated against the same, and the cooperating'surfaces of said base and plug forming a groove extending from a point of relatively small radius to a 'point of relatively large radius providing a restricted passage between said surfaces communicating at its end of relatively small radius with said bore and at its other end with said bearing surfaces, said passage having a cross-section so restricted that only sufficient oil to meet the lubrication requirements of said bearing surfaces: will pass therethrough incident to rotation of said shaft.

3. In a sewing machine a work support, a horizontally disposed hollow shaft beneath said work support, means for rotating said shaft, a rotary hook member carried by said shaft, a stationary member within said rotary member and having bearing surfaces in engagement therewith, a reservoir beneath said work support, an oil conduit connecting said reservoir with the bore of said hollow shaft, and centrifugal pumping means comprising separable members having cooperating surfaces forming an eccentrically disposed restricted channel in communication at one end with the bore of said shaft and at the other end with said bearing surfaces, said channel being arranged to be rotated about the axis of said shaft and having its end communicating with said bearing surfaces at a greater distance than its low shaft journaled in said frame beneath said work support, said shaft; having a longitudinally extending bore, a rotary hook having a rotary component mounted for rotation with said shaft, a stationary component within said rotary component and having bearing surfaces in cooperation therewith, an oil reservoir mounted directly beneath said work support and secured to the under surface thereof, an air-vent tube extending forwardlytroui said reservoir adjacent its top, a conduit connecting the bore of saidshaft with said reservoir, means within said bore for creating a centrifugal pumping action upon ro- 

